An example of a system which automatically locates retroreflective vehicle license plates and reads the alphanumeric characters on the license plates at a distance is taught in U.S. Pat. No. 4,491,923 (Look). The system operates in (at least) a two step process. First, the system illuminates a field of view through which vehicles pass. If a retroreflective license plate is within the field of view, the system detects the presence of a relatively small-sized but bright retroreflective image of the entire plate within the large field of view. Second, the system analyzes the license plate image by relying on the principle that the non-retroreflective or partially-retroreflective characters of the license plate number exhibit high contrast against the retroreflective plate background. The system uses a single source of illumination to detect the license plate and read the characters.